Intravenous (IV) therapy allows fluids to be infused directly into a vein. Compared to other fluid administration methods, IV therapy is one of the most efficient ways to deliver fluids to a patient. For infusion, a drip chamber is typically connected to the bottom of an IV bag contacting the fluid to be administered. Tubing is connected to the bottom of the drip chamber and can include means for intravenously inserting a needle or port though which the fluid is administered. The drip chamber permits gas (such as air) to escape from the fluid before the fluid enters a patient. In a patient, the inadvertent introduction of a gas bubble into a vein can result in what is called an embolism, which can in turn produce a blockage in a blood vessel. Many examples of the use of drip chambers by medical personnel to regulate the flow of intravenous fluids to a patient are known and disclosed in U.S. patents (see, e.g., U.S. Pat. Nos. 4,395,260, 4,601,712 and 5,776,109).
The use of a drip chamber also allows an estimate of the rate at which fluids are administered. For a fluid of a given viscosity, drips from a hole of known size will be of nearly identical volume and the number of drips in a minute can be counted. The rate of flow can be controlled, e.g., by a clamp on the infusion tubing. The clamp affects the resistance to flow, and provides increased pressure within the cup. However, other sources of resistance (e.g., whether the patient's vein into which fluids are being delivered is kinked or compressed by the patient's position) cannot be so directly controlled, and a change in position may change the rate of flow leading inadvertently to either too rapid or too slow infusion. In problematic cases such as this, an infusion pump or pressurized infuser may be used which gives a more accurate measurement of flow rate.
In order to minimize the possibility of introducing gas bubbles, and maintain the correct “head height” (typically 39″ to 42″) for gravity infusion, plus avoid backward flow through the line, it is preferable to keep the drip chamber and infusion apparatus elevated over the patient. However, in emergency situations it is not always possible and/or convenient to keep the drip chamber and infusion apparatus elevated over the patient. Another problem that can occur is that the drip chamber can open up when under pressure resulting from resistance provided by clamping to control drip rate or by vein compression.
Therefore, there is a need for a drip cup assembly which can function consistently, from any position, in any situation, and which can withstand increased internal pressure.